Fouling in magnums

I shoot a 300WM Sendero, factory barrel (can't wait to burn that sucker out...). I've always had some fouling issues, but I typically shoot ten or less shots per range session so it was manageable as I just foamed the barrel afterwards.

Lately I've been trying to empty some new cases to reload them for an upcoming elk hunt so I've been getting a lot more trigger time than usual -- more shots per session and more sessions. I've found that if I do not rigorously clean the barrel every ten shots or so, I only get 3-5 good shots in the next time before accuracy goes.

By rigorous cleaning I mean half dozen passes with Butch's Bore Shine alternating with bronze brush passes, a bore foam, and then a dozen more Butch's passes alternating with bronze brush passes. Typically I get a bunch of carbon out, followed by more copper with additional carbon.

The last time, even this was not enough. Last night I'd had it and after failing to ever get clean patches out (and not just the copper residue from the brush, but still carbon even after this long procedure) I plugged the barrel and filled it with copper solvent for 20min. This seemed to solve it, but this is making shooting a bigger pain than my muzzleloader.

Is this normal with these factory barrels? Can I expect better when I toast this one and get a custom barrel installed?

May I ask, are you shooting TSX solid copper bullets? Reason I ask is it sounds like a problem I had with two different rifles. I switched one to Bergers and the other to Nosslers and my problem went away.

I've heard that using bronze brushes with copper solvent will make it look like you still ahve copper residue because it tends to disolve the bronze brush a little. Not sure, but that's what I've heard.

I've heard that using bronze brushes with copper solvent will make it look like you still ahve copper residue because it tends to disolve the bronze brush a little. Not sure, but that's what I've heard.

It's quite easy to check if your barrel is copper fouled, if you're not sure about whether it is just coming off the brush or what...

Put a clean patch on a jag and run it up from the chamber end to about a half inch from the muzzle. Hold the rifle so the muzzle is at an angle to the light, and look down there. If you can see coppery coloured streaks on the rifling, yup, you've got copper fouling.

I go at the carbon first (bore foam is carbon-only), then the copper. Carbon seems to be the cuplrit in groups opening up while shooting, but residual copper seems to be at fault for subsequent strings getting shorter and shorter before accuracy goes (ie carbon is building up over copper).

Plastic brushes did not seem to remove the carbon effectively. I guess I was not clear but I know it's not the bronze brush causing the patches to continue looking bad, I've controlled for that.

I'd just use the barrel for a stake if it wasn't so darned accurate before the fouling builds up.

ATH, I have had some factory barrels do it too. Two that come to mind, but both were fouling with TSX's due to a rough bore not liking the solid coppers. I have never had a custom barrel do it. There are come lapping compounds out there and some bullets too that are suppose to help this. But I do not have any first hand exserience with them.